The main aims of this planning grant will be to constitute and strengthen a partnership between a multi-disciplinary research group from the biological, social, rehabilitation and population sciences, primarily based in South Africa and the United States, and to prepare, in the next 2 years, for a research program on developmental disabilities in children 2-6 years of age against the backdrop of a rampant HIV epidemic. Key preparatory activities will include the review of screening and assessment tools developed for 2-phase international childhood disability surveys and their adaptation for South African populations; the development of population screening methods for HIV infection in young children; the development and pilot testing of HIV counseling, consent and testing procedures within the context of multi-disciplinary professional assessments; and the development of a new tool for functional assessments of disability by mid-level rehabilitation workers. These methods and procedures and the proposed field and data operations will be field tested in a 2-phase childhood disability pilot study in a limited sample of 2000 children in the target age group. This pilot study will provide an approximation of the proportion of children likely to screening positive for disability, the proportion of these children likely to be confirmed on professional assessment and the HIV zero-prevalence rate in the general population of children in the 2-6 year age range. These studies will effectively prepare for the more rigorous design and more effective implementation of a 2-phase disability survey in South African children with the statistical power to provide precise and valid measures of the prevalence, types and causes of disability and the relative contribution of HIV infection to this disease burden. The task of preparing for and implementing this pilot study, with the active support and guidance of the US and consultant group, will serve as the key research training exercise in this planning grant and will develop the epidemiological insights and specific skills to undertake a future research program on 'Developmental Disabilities in the Time of HIV'.